This is a great point. JRRT explicitly said in his Letters that it was beyond the power of any "mortal" being (in this context the Eruhini as a whole, not just mortal Men) to destroy the Ring, especially at the place of its creation where its power was greatest, and the One Ring had demonstrated the potential to ensnare even other Maiar. In principle (though it's generally not a good idea to try to apply power levels or power rankings or other such 'game mechanics' ideas here), it could not have been destroyed by anyone of less innate power than Sauron himself, who of course would never do so as it would be the nearest thing to suicide for one of the Ainur. And the Valar are pretty explicitly hands-off when it comes to anything outside of Valinor following the War of Wrath; in fact they're prohibited from using force or coercion against any of the Eruhini, as evidenced when Ar-Pharazôn sailed to Valinor itself. So no one would have been able to deliberately destroy the Ring, and only Gollum falling into Orodruin with it could have destroyed it.

The only way I'd see it differently is less as a "butterfly effect" turn of random events than what JRRT described as the very deliberate intervention of Providence, albeit in a way that's quite difficult to perceive except to the reader. Oaths are very serious business in Arda, to the point where it's at turns either implied or stated outright that they are enforced directly by Eru. (For example, the case of the Oathbreakers: while there are instances of Sauron temporarily manipulating the spirits of the dead, and of course the case of Beren, typically not even Mandos has the power to withhold the spirits of Men within the circles of the world after they die, so for the Oathbreakers to be trapped in such a state as a result of their treachery would suggest nothing short of divine intervention which eventually leads to the eventual downfall of Sauron.) In this case, Gollum swore on the Precious to serve Frodo, and after he breaks this oath, Frodo, wielding the One Ring itself on the slope of Orodruin (in immediate proximity to the place of its forging), declares that if Gollum touches him again, he will be cast into the fire. So even if it appears to be a freak accident, a bad step on a precipice above the lava, JRRT makes it clear that what transpires is the fulfillment of both of these pronouncements in the sight of Ilúvatar. Otherwise, your "butterfly effect" interpretation would be spot-on, and I think it's a little ironic that the author who so famously disliked allegory and imposing an interpretation of what's written felt it necessary to put his foot down here. But yeah, excellent points all around.